1. Technical Field
The present invention relates to a liquid ejecting apparatus that ejects liquid from nozzles and a method for controlling a liquid ejecting head.
2. Related Art
An ink-jet printer is known as an example of a liquid ejecting apparatus that ejects liquid onto a target in the form of droplets. The ink-jet printer prints an image or the like on paper by discharging ink droplets onto the paper. Such a printer moves a recording head in the main scan direction and paper in the sub scan direction. Mounted on a carriage, the recording head and ink cartridges reciprocate. Lines of nozzles are formed in the bottom surface of the recording head. The ink cartridge is in communication with the nozzle line through a flow passage. Ink flows from the ink cartridge to the nozzle line through the flow passage. In the field of such a recording head, JP-A-2007-50581 discloses the following technique. A flow passage branches from one ink cartridge into a plurality of branch passages, which is connected to a plurality of nozzle lines. The positions of the nozzle lines are shifted in the sub scan direction. To make conditions such as pressure inside flow passages uniform, ink is sucked from the plurality of nozzle lines.
There is a demand for mounting a plurality of ink cartridges of the same color on a carriage and reducing the frequency of ink-cartridge replacement. However, if the above technique of providing a flow passage that branches from one ink cartridge for connection to a plurality of nozzle lines is applied to such an application in which a plurality of ink cartridges of the same color is mounted on a carriage, the proportion of the number of the ink cartridges to the number of the nozzle lines shifted in the sub scan direction is limited to an integral multiple, which means that there is little room for flexibility. In order to reduce the frequency of ink-cartridge replacement, it is necessary to ensure that the amount of ink contained in the plurality of ink cartridges of the same color should decrease at the same speed. However, if the proportion of the number of the ink cartridges to the number of the nozzle lines shifted in the sub scan direction is not limited to an integral multiple, it is impossible to consume ink contained in the plurality of ink cartridges equally.